Flashcards in Gastrointestinal System (Test 3) Deck (38)
What is the major function of gastrointestinal system?
To digest and absorb nutrients.
What is the effect of histamine on acid secretion in the stomach?
Increases acid secretion
In perietal cell, what processes mediate HCl secretion?
H+ and Cl- are secreted separately via two different pathways. H+ is generated from H2O and CO2 in perietal cells with the help of carbonic anhydrase, and secreted by H+/K+-ATPase pump into lumen. Cl- is transferred into the cell by basolateral membrane HCO3--Cl- exchanger, and exit into lumen via Cl channel.
In the stomach, H+ ions are secreted in exchange for?
What is secretin?
Secretin is a hormone secreted by the endocrine cells of the small intestine, it stimulates the pancreas to release bicarbonate ions
What is the advantage of enzymatic hydrolysis?
Enzymatic hydrolysis is faster than hydrolysis in the absence of an enzyme.
Cholecystokinin is released in what cells in the presence of fats?
The duodenal mucosal cells.
What is the role of bile salts in digestion?
Emulsifying agents for large fat droplets in the upper intestinal tract
In what form are dietary carbohydrates absorbed in the small intestine?
Monosaccharides. (Sucrose and lactose are disaccharides)
Where do dietary carbohydrates go after absorption?
They are transported to the liver via the hepatic portal vein after breakdown to simpler monosaccharides.
What is required for efficient absorption of fats in the alimentary tract?
The presence of a pancreatic lipase.
Is the polysaccharide cellulose digested in the body?
Yes. It is partially digested by bacteria in the colon. However, cellulose cannot be broken down by small intestinal enzymes.
Where are the products of digestion absorbed?
The products of digestion are absorbed across the intestinal epithelial cells.
In what form is dietary lipid absorbed by the small intestine transported in the lymph?
What are the stimuli for gastrointestinal reflex?
Distention of the wall by the volume of the luminal contents, increase in chyme concentration of specific digestion products, increase of chyme osmolarity, increase of chyme acidity etc.
What cells does the submucosal plexus directly act on?
Endocrine and secretory cells.
Is GI activity regulated by short and long neural reflexes?
If enteric nervous system is a part of autonomic nervous system, do they use epinephrine, norepinephrine and acetylcholine as their transmitters only?
No. enteric nervous system is similar to CNS, using as much as 30 different neurotransmitters.
What is secreted by gastric chief cells?
What volume of fluid is secreted daily into the GI tract?
Where do water and electrolytes get absorbed in GI tract?
Where are exocrine and endocrine cells located in the GI tract?
The epithelial layer.
What is the advantage of the existence of proenymes for pancreatic enzymes?
To facilitate safe storage.
What is the function of microvilli in the small intestine?
Microvilli greatly increase the surface area for absorption of nutrients
What are the substances/condition that stimulates acid secretion in the stomach?
Gastrin, histamine, acetylcholine, distention of the stomach
Where is gastrin secreted?
Antrum of the stomach.
What consist of micelles?
Bile salts, fatty acids, phospholipids and 2-monoglycerides.
Is vitamin B12 a water-soluble vitamin?
Yes, it binds to the intrinsic factor (IF) which is secreted by the parietal cells of the stomach. The IF-vitamin B12 is absorbed by endocytosis at ileum
What is the size of micelles?